A strong believe of mine: there is no storage, only communication. I hold that thought since I first heard of SRAM, and I think it applies to everything, knowledge, technology, societies, our universe in general..
Unpowered SSDs slowly lose data
181–190 of 341 posts
Re: Unpowered SSDs slowly lose data
#182Earlier quoted context omitted.
Because no one is willing to pay for SLC. Those QLC NAND chips? Pretty much all of them have an "SLC mode", which treats each cell as 1 bit, and increases both write speeds and reliability massively. But who wants to have 4 times less capacity for the same price?
4 times less capacity but 100x or more endurance or retention at the same price looks like a great deal to me. Alternatively: do you want to have 4x more capacity at 1/100th the reliability? Plenty of people would be willing to pay for SLC mode. There is an unofficial firmware hack that enables it: https://news.ycombinator.com/item?id=40405578 1TB QLC SSDs are But why won't the manufacturers let you choose? The real…
The real answer is: no one actually cares.
Very few people have the technical understanding required to make such a choice. And of those, fewer people still would actually pick SLC over QLC.
At the same time: a lot of people would, if facing a choice between a $50 1TB SSD and a $40 1TB SSD, pick the latter. So there's a big incentive to optimize on cost, and not a lot of incentive to optimize on anything else.
This "SLC only" mode exists in the firmware for the sake of a few very specific customers with very specific needs - the few B2B customers that are actually willing to pay that fee. And they don't get the $50 1TB SSD with a settings bit flipped - they pay a lot more, and with that, they get better QC, a better grade of NAND flash chips, extended thermal envelopes, performance guarantees, etc.
Most drives out there just use this "SLC" mode for caches, "hot spot" data and internal needs.
Re: Unpowered SSDs slowly lose data
#183One key point about retention which is not often mentioned, and indeed neither does this article, is that retention is inversely proportional to program/erase cycles and decreases exponentially with increasing temperature. Hence why retention specs are usually X amount of time after Y cycles at Z temperature. Even a QLC SSD that has only been written to once, and kept in a freezer at -40, may hold data for several de…
> Even a QLC SSD that has only been written to once, and kept in a freezer at -40, may hold data for several decades. So literally put your data in cold storage.
That is literally the origin of the term.
Re: Unpowered SSDs slowly lose data
#184Re: Unpowered SSDs slowly lose data
#185Earlier quoted context omitted.
no, the firmware does any maintenance. good firmware should do gradual scrub whenever it's idle. unfortunately, there's no real way to know whether the firmware is good, or doing anything. I wonder if there's some easy way to measure power consumed by a device - to detect whether it's doing housekeeping.
Honestly this is one of my favorite things about ZFS. I know that a disk scan is performed every week/month (whatever schedule). And I also know that it has verified the contents of each block. It is very reassuring in that way.
In threads like this I keep hearing about ZFS. What would be the drawbacks of running ZFS as a home user? I keep my OS on the SSD and my files on spinning rust, if that's relevant.
Re: Unpowered SSDs slowly lose data
#186Earlier quoted context omitted.
4 times less capacity but 100x or more endurance or retention at the same price looks like a great deal to me. Alternatively: do you want to have 4x more capacity at 1/100th the reliability? Plenty of people would be willing to pay for SLC mode. There is an unofficial firmware hack that enables it: https://news.ycombinator.com/item?id=40405578 1TB QLC SSDs are But why won't the manufacturers let you choose? The real…
The real answer is: no one actually cares. Very few people have the technical understanding required to make such a choice. And of those, fewer people still would actually pick SLC over QLC. At the same time: a lot of people would, if facing a choice between a $50 1TB SSD and a $40 1TB SSD, pick the latter. So there's a big incentive to optimize on cost, and not a lot of incentive to optimize on anything else. This "…
Agreed. I have some technical understanding of SLC’s advantages, but why would I choose it over QLC? My file system has checksums on data and metadata, my backup strategy is solid, my SSD is powered most days, and before it dies I’ll probably upgrade my computer for other reasons.
Re: Unpowered SSDs slowly lose data
#187What about powered SSDs that contain files that are rarely read? My desktop computer is generally powered except when there is a power failure, but among the million+ files on its SSD there are certainly some that I do not read or write for years. Does the SSD controller automatically look for used blocks that need to have their charge refreshed and do so, or do I need to periodically do something like "find / -type…
Maybe tangentially related to my Pixel phone losing photos [0]?
Re: Unpowered SSDs slowly lose data
#188I was in a team that wrote the firmware to handle that 15 years ago, with focus on automotive implementations where temperature might be high and access to the data is harder.
Re: Unpowered SSDs slowly lose data
#189well poop, I was just about to buy an 8Tb ssd to use as a backup device
Re: Unpowered SSDs slowly lose data
#190Earlier quoted context omitted.
Would an airtight container and liberal addition of dessicants help?
Sure. Just make sure the drive is warm before you take it out of the container - because this is when the critical condensation happens: you take out a cold drive an expose it to humid room temperature air. Then water condenses on (and in) the cold drive. Re-freezing is also critical, the container should contain no humid air when it goes into the freezer, because the water will condense and freeze as the container c…
A vacuum sealer would probably help to avoid the humid air, too.